Apparatus for sorting the conductors of a multiconductor cable



Nov. 4, 1 969 A. w, ROLLINS ETAL 3,476,888

APPARATUS FOR SORTING THE CONDUCTORS OF A MULTICONDUCTOR CABLE 2 Sheets-Sheet 1 Filed May 25, 1966 m wm EN m N v U GU ummm Nu 5m QWEN mmm E VI mom A M m A DSQEEQ H b QUEEQQX H B n H m Ex :o umm QQN ATTORN 3.

A. W. RQLLINS ET AL APPARATUS FOR SORTING THE CONDUCTORS Nov. 4. 1969 OF A MULTIC ONDUCTOR CABLE 2 Sheets-Sheet 2 Filed May 25, 1966 INVENTORS.

fillberf W. Rollins Rona/cl A7. Rollins A F k United States Patent 3,476,888 APPARATUS FOR SORTING THE CONDUCTORS OF A MULTICONDUCTOR CABLE Albert W. Rollins, 911 Valley Lane 64150, and Ronald A. Rollins, Rte. 24 64152, both of Parkville, Mo. Filed May 25, 1966, Ser. No. 553,602 Int. Cl. H04m 3/22 US. Cl. 179-175.25 Claims ABSTRACT OF THE DISCLOSURE Cable sorting apparatus having a master unit for connection to one end of the cable to be sorted, and a remote unit for connection to the cable at a location remote from the master unit. The master unit comprises x and y control sections, a switching section, a sorting monitor display, and sorting terminals. The remote unit comprises x and y command circuits, an x-y identification display, and sorting terminals. The cable is connected between the sorting terminals of the two units and control terminals associated with the x and y command and control functions. The x-y address information is initiated by a technician at the remote unit site through the use-of the x and y command circuits, and the master unit responds by energizing the conductor having the address of interest. The x-y identification display in the remote unit responds to the energized conductor to indicate its remote unit address, which is then changed if required .by reconnecting the conductor to the remote unit sorting terminal of like address.

This invention relates to apparatus for identifying the conductors of a multiconductor cable at a location spaced along the cable from a location where the conductors are identified.

In telephone systems, intercommunication networks and other applications where multiconductor cables are commonly utilized, the problem of identifying the conductors at an end of the cable where connections are to be made is presented. Color coding is a satisfactory identification aid in cables where a large number of conductors are not contained within a single sheath but, in larger cables containing several hundred conductors or more, other techniques must be utilized to identify the conductor ends before the latter are connected to terminal boards or the system equipment.

A conventional technique in the identification of conductors of large cables is to probe the conductor ends while a signal is applied at another location along the cable where the conductors have previously been identified. Manifestly, this requires two technicians, one at the site of previous identification, and one at the new, remote location. Additionally, the probing technique is time-consuming and commonly requires that each conductor be tagged or marked in some suitable manner as sorting progresses in order to preserve its identification.

It is, therefore, an important object of this invention to provide cable sorting apparatus which will identify the conductors of a multiconductor cable at a remote location therealong by operation of the apparatus from the remote location only, so that the necessity of providing a second technician is obviated.

As a corollary to the foregoing object, it is an important aim of this invention to provide such apparatus that will both rapidly effect sorting of the conductors and preserve the identification thereof for subsequent connection to terminal boards or system equipment.

It is also an important object to provide cable sorting apparatus having means for identifying cable conductors based upon arbitrary addresses assigned to the conductors at a location spaced along the cable from the conductor identification means, so that the ends of each conductor at the two locations may be identified by a particular address during the sorting operation without prior identification of one of theconductor ends being required.

Another important object is to provide apparatus as aforesaid having a master unit adapted for connection to one end of a cable to be sorted, and a remote unit adapted for connection to the other end of the cable, wherein the units are provided with circuitry for exciting each condoctor to identify the latter through a closed electrical circuit formed entirely by the cable itself, so that an external current return path between the units is not required.

A further object is to provide apparatus as aforesaid wherein the conductor terminations at the master unit are assigned 'x-y coordinate addresses, and wherein the remote unit has command means operable to select each conductor address for remote unit identification of the conductor having the selected address.

Another object is to provide the master unit with a sorting monitor which displays the x-y coordinates of each conductor as the cable is sorted; thus, a technician at the master station will be aware of the progress of the sorting operation so that connections may be made to the sorted conductors as the sorting operation progresses.

Further objects are to provide means for accomplishing sorting in a step-by-step fashion from conductor to conductor in directions of increasing x-y coordinate addresses; to provide command means as aforesaid capable of initiating operation in the master unit which will reset the later at the lowest coordinate address; and to provide a communication circuit between the units which is established after the remote end of the conductor having the lowest coordinate address is identified.

In the drawings:

FIGURE 1 is a block diagram of the sorting system;

FIG. 2 is a schematic diagram showing the sorting materials, the x-y display, and the communication circuit of the remote unit;

FIGS. 3 and 4 illustrate the x and y command circuits, respectively, of the remote unit;

FIG. 5 is a schematic diagram of the entire master unit; and

FIG. 6 is an equivalent circuit illustrating the manner in which a current return path is established in the cable.

In FIG. 1, the master unit of the instant invention is illustrated at 10 and comprises an x control section 12 having control terminals C and C a y control section 14 having control terminals C and C a switching section 16, a sorting monitor display 18, and sorting terminals T. The remote unit 20 comprises an x command circuit 22 having control terminals 0, and C a y command circuit 24 having control terminals C and C an x-y identification display 26, and sorting terminals T. A multiconductor cable 28 to be sorted includes conductors 28a which extend between sorting terminals T and T, and four conductors 28b extending between respective pairs of control terminals C1-C1, (lg-(32, C -C and C4C4- In utilizing the invention, the ends of conductors 28a are connected to the master unit sorting terminals T and the remote sorting terminals T for identification of the conductor ends at terminals T in accordance with addresses assigned to terminals T in a manner to be fully described hereinafter. The four conductors 2812 are identified before sorting begins and are utilized as control lines. The terminal addresses assigned to the master unit sorting terminals T are in the form of x-y coordinates, identification being effected by indicator lights at the remote xy display 26 which, when illuminated, indicate the particular terminal T to which a conductor having a known master unit sorting terminal address is connected. Address information is initiated by the technician at the re- 3 mote unit site through the use of the x and y command circuits 22 and 24. It should be understood that the address information delivered to the master unit along control lines 281; is known to the technician at the remote site and that, through the action of the x and y control sections 12 and 14 and the switching section 16, the conductor 28a having this address is energized. The remote display 26 responds to the energized conductor and indicates its address at the remote unit which, most likely, is different from its master unit sorting terminal address. The technician may then reconnect this conductor to the terminal T having the address of the corresponding terminal T; the procedure is then repeated for each additional address command until the entire cable is sorted.

MASTER UNIT The master unit is shown in detail in FIG. 5. Six of the master unit sorting terminals T are illustrated adjacent the upper margin of the figure. Each of these terminals is designated by a particular address(26, 1), (1, 1), (2, 1), (26, 2), (1, 2), and (2, 2) from left to right. Each of these addresses consists of a pair of coordinates of an x-y address system, the first number being the abscissa and the second number being the ordinate. The apparatus to be described hereinafter has a 260 sorting terminal capacity; therefore, it should be understood that the six terminals T shown in FIG. represent six of a possible total of 260 sorting terminals.

An x-direction stepper relay 30 has a relay coil 32 associated with the x control section 12, and twelve, 26 position rotary poles forming a part of switching section 16. Four of the poles of relay 30 are illustrated and are designated 34, 36, 38 and 40, the latter being shown schematically as a normally closed switch.

The x control section 12 includes a step-down transformer 42, an electromechanical relay having a coil 44 and a normally open relay switch 46, a second electromechanical relay having a coil 48 and a normally open switch 50, an electromechanical pulser 52, and a set of homing contacts 54 mechanically coupled with the armature of stepper relay coil 32 and illustrated in the open position corresponding to the reset condition of the stepper 30. The primary winding of transformer 42 is connected to a pair of power terminals 56 which may be connected to an available alternating current source, such as 110 volts AC. The upper end of the secondary winding of transformer 42 is connected by a lead 58 to relay coil 44, and by a diode 60 to the stationary contacts of relay switches 46 and 50. A diode 62, a capacitor 64, and a resistor 66 are connected in parallel with one another and across coil 44, and connect lead 58 with control terminal C The lower end of the secondary winding of transformer 42 is connected by a lead 68 to relay coil 48, which also has a diode 70, a capacitor 72, and a resistor 74 connected in parallel thereacross between lead 68 and control terminal C Closure of relay switch 46 effects energization of stepper coil 32 to cause the stepper to advance by establishing a power circuit through coil 32 as follows: From diode 60 to switch 46, along a lead 76 to coil 32, and then along a lead 78 to lead 68. A filter capacitor 80 is connected between lead 78 and the cathode of diode 60; therefore, coil 32 is supplied with essentially a direct current. Closure of relay switch 50' establishes a power circuit to stepper coil 32 which effects resetting of stepper 30 as follows: From diode 60 to switch 50, along a lead 82 to homing contacts 54 (which would be closed prior to resetting), along a lead 84 to pulser 52, along a lead 86 to coil 32, and thence along lead 78 to lead 68. Series connected resistor 88 and diode 90 are connected in parallel with coil 32 and serve as a surge suppressor.

A y-direction stepper relay 92 has a relay coil 94 associated with y control section 14, and three, position poles 96, 98 and 100 forming a part of switching section 16. Pole 100 is diagrammatically illustrated as a normally closed switch. The components and circuit arrangement .4 of y control section 14 are identical to that as described above for x control section 12; therefore, the various components and leads in section 14 are designated by the same reference characters as utilized in the description of section 12, with the addition of the a notation. Note, however, that control terminals C and C are connected to the cathodes of diodes 62a and 70a respectively.

Switching section 16 is supplied with alternating current at power terminals 102 and 104, the latter being connected to pole 38 of stepper 30, and poles 96 and 98 of stepper 92 by lead 106. Poles 34 and 36 of stepper 30 are energized by current flowing in leads 108 and 110, respectively, which are connected to the fixed contacts associated with pole 96 designated 1 and 2. The contact designations associated with poles 96 and 98 represent ordinate values of the addresses of sorting terminals T; likewise, the designations of the fixed contacts associated with poles 34, 36, and 38 represent abscissa values of the addresses of sorting terminals T.

Both stepper relays 30 and 92 are shown in their reset conditions wherein sorting terminal T(1, 1) is energized as follows: From power terminal 104 along lead 106 to pole 98, along lead 108 to pole 34, and thence along a lead 112 to poles 40 and which form a series path to a lead 114 connected to sorting terminal T( 1, 1). Terminal T(26, 1) is connected to contact 26 of pole 34 by a lead 116, terminal T(2, 1) is connected to contact 2 of pole 34 by a lead 118, terminal T(26, 2) is connected to contact 26 of pole 36 by a lead 120, similar connections being made between the remaining two sorting terminals illustrated and associated contacts of pole 36 by leads 122 and 124 as illustrated.

A line 126 connected to supply terminal 102 forms a current return path and is connected to leads 116, 112, 118, 120, 122 and 124 by resistors 128, 130, 132, 134, 136 and 138 respectively. Line 126 also connects with one electrical side of each of a number of indicators 140 of the master unit monitor display 18. Indicators 140 may be in the form of incandescent lamps and are arranged as illustrated along imaginary x and y axes. The broken line rectangle 142 represents a panel which would form a part of the housing of the master unit apparatus; therefore, indicators 140 would form panel lights extending in x and y directions, it being understood that only three of the 10 y-direction indicators and three of the 26 x-direction indicators are illustrated.

Pole 38 controls the energization of the abscissa indicators 140 by virtue of leads 144, 146 and 148 which extend from the three fixed contacts thereof illustrated to the indicators 140 corresponding to abscissa values of 1, 2 and 26 respectively. Current is supplied to pole' 38 by a lead 150 connected to lead 106. In similar manner, pole 98 (connected to lead 106) controls the energization of the y-direction indicators by virtue of leads 152, 154 and 156 which extend from the fixed contacts thereof to the indicators 140 representing ordinate values of 1, 2 and 10 respectively.

A communication circuit is illustrated at the upper lefthand portion of FIG. 5 and includes a carbon microphone 158 connected in a series loop with an amplifier stage 160, and the primary of a transformer 162. A headset or receiver 164 is connected across the secondary of transformer 162 unless poles 40 and 100 close against their contacts in a manner to place a direct short across the transformer secondary; this occurs when both of the steppers 30 and 92 are reset, but not otherwise. A normally open, hang-up switch 166 is also connected across the transformer secondary to silence the communication circuit upon closure thereof such as by resting receiver 164 thereupon as in conventional telephone instruments. Amplifier stage may be provided with a tone oscillator for testing the frequency response of the cable being sorted. The frequency of oscillation would preferably be initially at dial-tone frequency and increase with time to cover the test spectrum.

REMOTE UNIT FIGURE 2 shows the remote display 26 in detail and illustrates the connection of sorting'terminals T therewith. The broken line rectangle 168 diagrammatically illustrates a panel or display board which mounts 260 indicating devices 170 in an array which forms an x-y display. To simplify the illustration, only eight of the devices 170 are shown. As in the case of indicators 140, devices 170 may comprise panel lights. 1

It will be noted that eight of the 260 sorting terminals T' are illustrated in FIG. 2 and are designated by xy coordinate addresses. These addresses range from (1, 1)

to (26, in the x and y directions; thus, each of the terminals T carries a designationwhich is the same as the address of a corresponding master unit sorting terminal T.

In practice, board 168 would be provided with address indicia adjacent each light 170 or disposed such that the indicia would be illuminated by the corresponding light upon energization of the latter. Lights 170 are interconnected by a common lead 172; leads 174, 176, 178, 180, 182, 184, 186 and 188 connect respective terminals T to the corresponding lights 170 as illustrated.

A headset or receiver 190 is interposed in series with lead 180 and forms a part of a communication circuit 192 which includes a carbon microphone 194, a current limiting resistor 196, and a battery 198 connected in a series loop with the primary of a transformer 200. Receiver 190 is connected across the secondary of transformer 200, together with a normally open hang-up switch 202.

Referring to FIG. 3, x command circuit 22 comprises a normally open, push-button operated reset switch 204, a normally open, push-button operated step switch 206, and a pair of diodes 208 and 210. Switch 204 and diode 208 are connected in series across control terminals C and C and switch 206 and diode 210 are likewise connected in series across .these control terminals. Diode 208, however, has its anode connected to terminal C while diode 210 has its cathode connected to terminal C The y command circuit 24 is shown in detail in FIG. 4 and comprises a normally open, push-button operated reset switch 212, a normally open, push-button operated step switch 214, and a pair of diodes 216 and 218. Switch 212 and diode 216 are connected in series between control terminals C and C as are switch 214 and diode 218. Note that the anode of diode 216 and the cathode of diode 218 are connected to terminal C OPERATION In the discussion to follow it will be assumed that it is desired to sort the conductors of a multiconductor cable so that, after sorting, the conductor terminations at each end of the cable may be connected to appropriate terminals or connection points of a terminal board or a piece of electrical equipment. The master unit 10 and the remote unit 20 are located at opposite ends of the cable, as illustrated in FIG. 1. The only connection between the two units is by way of the cable conductors themselves, illustrated at 28a and 28b.

Initially, at the master unit, conductors 28:: are connected at random to sorting terminals T, except for four of the conductors 2811 which must be connected to the control terminals C -C Since a total of 264 control and sorting terminals are available, it will be appreciated that, if cable 28 has fewer than 264 conductors, the conductors 28a would be connected to sorting terminals T in an orderly fashion, i.e., for a cable having 100 conductors available for connection to terminals T, a suggested approach would be to utilize terminals T having addresses of (1, 1) through (10, 10). Terminals T should be arranged on an instrument panel in the form of an xy array with the addresses thereof indicated by appropriate indicia.

After the master unit terminals are loaded, the operator may then leave the master unit location and proceed to the opposite end of the cable. Before leaving, however, steppers 30 and 92 are placed in the reset condition illustrated in FIG. 5. This may be accomplished by providing auxiliary x and y command circuits identical to the circuits 22 and 24 illustrated in FIGS. 3 and 4. Such auxiliary circuits would be directly connected to control terminals C C and C C in the same manner as circuits 22 and 24 are connected to terminals C C and C C Since conductors 28b have not as yet been identified at the remote unit, the x and y command circuits 22 and 24 will be ineffective; hence, initial resetting of the steppers must be accomplished at the master unit. The manner in which the command circuits initiate stepping and resetting of the steppers will be explained hereinafter.

At the remote unit, the operator commences connecting the cable conductors to sorting terminals T' at random. As the conductors are connected, two of the lamps will light, indicating that two of the conductors 28b have been identified. Energization of two lamps 170 occurs, for example, by virtue of current flow along the two conductors 28b extending between terminals C and C and the two sorting terminals T to which they are connected. It will be appreciated that the two lamps 170 connected to these two sorting terminals will light due to the series connection effected by lead 172. A closed circuit is established in similar fashion when the two conductors 28b, connected to control terminals C and C are connected to sorting terminals T. When conductors 28b are identified, they are re-connected to terminals C '-C To verify the command circuits, step switches 206 and 214 are depressed. If either switch fails to initiate a step function, the two conductors 2812 connected to the associated control terminals are reversed. When the proper polarity is established, the step switch 214 is repeatedly operated while display 26 is observed to ascertain if the sequential lighting of lamps 170 thus produced, corresponds to the ten step capacity of y stepper 92. This will be readily apparent since the x stepper 30 has 26 positions, while y stepper 92 has only 10. This verification procedure, of course, is instituted after all of the conductors 28a have been connected to sorting terminals T.

During connecting of the cable conductors to sorting terminals T, a condition will occur in which one of the lamps 17 0 lights. This identifies the conductor 28a having the (1, 1) master unit sorting terminal address. This conductor, therefore, is connected to remote unit sorting terminal T(1, 1), thereby preserving the identification of this conductor and establishing a communication line between the two units which may be utilized when two operators are employed. As stated earlier, sorting may be accomplished by only one operator; however, it may be desired to use two operators for a purpose to be discussed hereinafter.

After the control lines 28b are properly connected to control terminals C C of the remote unit, and the conductor 28a having the (1, 1) address is connected to sorting terminal T(1, 1), sorting of the remainder of the conductors 28a is initiated by momentarily closing one of the step switches 206 or 214. Assuming that the operator desires to sort in the y direction at each x step, y c0mmand step switch 214 is operated to energize stepper coil 94 and shift poles 96 and 98 into engagement with their associated fixed contacts designated 2. Since the cathode of diode 118 is connected to control terminal C relay coil 44a is energized by current flow through the following circuit: From the secondary of transformer 42a, along lead 68 through diode 70a to control terminal C along the associated conductor 28b to control terminal C through switch 214 and diode 218 to control terminal C along the associated conductor 28b to terminal C and thence through relay coil 44a and along lead 58a to the transformer secondary. Note that diode 62a is poled such that current will flow through coil 44a after capacitor 64a becomes charged. Capacitor 64a, therefore, operates as a filter capacitor to reduce the ripple factor of the unidirectional current flowing through coil 44a. Energization of coil 44a closes relay switch 46a to, in turn, energize stepper coil 94 and advance poles 96 and 98 to the next position.

At this juncture, it is instructive to note the current path through the apparatus which enables a particular lamp 170 in the remote display 26 to become energized without the use of an external electrical return. Assuming that excitation is being applied to the master unit sorting terminal T(1, 1) as illustrated in FIG. 5, the following circuit is created: From T(1, 1) to T'(1, 1) along the interconnecting conductor 2811, through headset 190 and the secondary of transformer 200 to lead 180 and the lamp 170 connected thereto to energize the latter, along lead 172 to all of the other lamps 170 of display 26, through these lamps to the respective terminals T, then along the other conductors 28a to all of the other master unit sorting terminals T being utilized, then through resistors 128, 132, 134, 136, 138 and the resistors (not shown) of the unillustrated terminals T to line 126, and thence along line 126 to power supply terminal 102. Thus, it will be appreciated that the unlit lamps 170 and the resistors associated with the unexcited sorting terminals T establish circuit continuity.

The equivalent circuit of FIG. 6 simply illustrates the manner in which circuit continuity is established. The reference numerals utilized in the circuit of FIG. 6 illustrate the return path when conductor 28a, having an address of 1, 1), is energized, as above. Lamp 170(1, 1) is lit, while the other bulbs and associated resistors form parallel paths interconnecting lead 172 in the remote unit with line 126 in the master unit. Each path through an unlit lamp 170 and its associated resistor in the master unit has a relatively high impedance, but the parallel combination of all the series connected unlit lamps and resistors provides a low impedance connection. It will be appreciated that, if the entire circuit were illustrated in the drawings, there would be 259 series connected unlit lamps and resistors.

It will be noted that, if hang-up switch 202 is open, alternating current will pass through headset 190 when the steppers are in the reset condition illustrated. The line frequency tone thus produced gives the operator a verification that both of the steppers are reset.

Relay coil 48 in the x control seciton of the master unit is energized by closing step switch 206 in the x command circuit of the remote unit, and operation of the x control section to energize stepper coil 32 is accomplished in the same manner as discussed above for the y control section 14. The operator proceeds from address to address by operating step switches 206 and 214 in an orderly fashion so that the operator is at all times aware of the address command being delivered to the master unit control sections. As each conductor is energized, one of the lamps 170 will light. Unless by chance, the energized lamp will not indicate a terminal address at the remote unit which is the same as the terminal address being delivered by the command circuits to the master unit. Thus, each conductor 28a at the remote unit will normally have to be reconnected to the appropriate terminal T. This preserves the address of each conductor as sorting progresses.

For two-man operation, the master display 18 is useful as a monitor so that the operator at the master unit will be aware of sorting progress. Thus, conductors which have been sorted may be disconnected from the master unit sorting terminals and reconnected to system equipment or terminal boards.

Resetting of either of the steppers is accomplished by control sections 12 and 14 in the same manner upon operation of the appropriate reset switch 204 or 212. Assuming that stepper 30 is to be reset, closure of reset switch 204 establishes the following electrical circuit in 2: control section 12 by virtue of the polarity of diode 208: From the secondary of transformer 42 along lead 58 through diode 62 to control terminal C along the corresponding control line 28b to terminal C through diode 208 and switch 204 to control terminal C along the corresponding control line 28b to terminal C and thence through relay coil 48 and lead 68 to the transformer secondary. In the reset mode, the action of diode 62 prevents energization of relay coil 44, but diode 70 permits current to fiow through relay coil 48 after capacitor 72 charges. This closes relay switch 50 and energizes pulser 52, the latter being a conventional device in the form of a solenoid having series contacts and a spring return, the contacts opening intermittently to break the power circuit to the solenoid and permit contact reclosure under the action of the return spring. This pulses stepper coil 32 to cause the latter to step rapidly through its positions until the reset position is reached, whereupon homing contacts 54 open to de-energize pulser 52.

The 264 terminal sorter illustrated could be utilized to sort cables having several times as many conductors as the number of sorting terminals. This is accomplished by using a number of remote units, in which case the remote units are loaded with all the conductors and the master unit with its capacity, 264 in the instant example. After sorting until one remote unit is properly connected to its associated conductors, the sorting operation proceeds to the remaining units in succession.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Apparatus for sorting the conductors of a multiconductor cable, said apparatus comprising:

a master unit provided with sorting terminals having predetermined individual terminal addresses, and control terminals, both of the same being adapted for coupling to respective individual conductors,

said unit having means coupled with said control terminals and said sorting terminals and responsive to address information delivered to the control terminals for exciting the sorting terminal identified by said information; and

a remote unit provided with sorting terminals and control terminals, both'of the same being adapted for coupling to respective individual conductors at a location spaced along said cable from said master unit terminals,

said remote unit having command means coupled with the control terminals thereof for providing said information at the remote unit control terminals whereby, when electrical continuity is established between the control terminals of the master and remote units, excitation of the conductors coupled to the master unit sorting terminals is controlled from th remote unit, 1

said remote unit being provided with means coupled with the sorting terminals thereof for indicating the remote unit sorting terminal to which an excited conductor is coupled, whereby to locate the conductor having the master sorting terminal address fed to said exciting means.

2. The invention of claim 1,

said exciting means and said indicating means having circuitry cooperating to render the indicating means operable to identify the conductors coupled to the master unit control terminals as the last-mentioned conductors are coupled to the remote unit sorting terminals, whereby to provide said electrical continuity when such identified conductors are coupled to the remote unit control terminals.

3. The invention of claim 1,

said indicating means including a plurality of electrically responsive indicating devices coupled with respective remote unit sorting terminals,

said units having circuit means coupled with the master and remote sorting terminals for establishing a return path through said cable for current flowing between the units in the excited conductor, whereby the devices are energized by current supplied by the master unit wtihout utilizing an electrical return externally of the cable.

4. The invention of claim 1,

said exciting means including a pair of electrical connection points adapted for coupling with a source of electrical energy, an impedance-presenting element coupled between one of said points and each of said master unit sorting terminals respectively, and means coupled with the other of said points for establishing electrical continuity between said other point and the master unit sorting terminal identified by said information,

said indicating means including a plurality of electrically responsive indicating devices coupled between a common junction and respective remote unit sorting terminals, whereby to provide a return path through said cable for current flowing between the units in the excited conductor.

5. The invention of claim 1,

said addresses of the master unit sorting terminals being in the form of x-y coordinates,

said indicating means including a plurality of electrically responsive indicating devices, structure mounting said devices in a manner to provide an x-y display with each device representing a pair of said coordinates, and circuit means coupling said devices to respective remote unit sorting terminals whereby, as each conductor having a particular master sorting terminal address is located by energization of one of said devices, the located conductor may be coupled to the remote unit sorting terminal of like address to preserve its identification.

6. The invention of claim 5,

said units having circuit means coupled with the master and remote sorting terminals for establishing a return path through said cable for current flowing between the units in the excited conductor, whereby the devices are energized by current supplied by the master unit without utilizing an electrical return externally of the cable.

7. The invention of claim 5,

said master unit being provided with a sorting monitor display comprising an electrically responsive indicator representing each abscissa and ordinate respectively of said coordinates,

said exciting means having switching circuitry for energizing the pair of said indicators representing the address of the master unit sorting terminal identified by said information.

8. The invention of claim 5,

said exciting means including first and second electrically responsive switching means operable to effect excitation of said master unit sorting terminals in x and y direction succession respectively, and control means provided with an x control section coupled with said first switching means for energizing the latter to advance master unit sorting terminal excitation in the x direction, and a y control section coupled with said second switching means for energizing the latter to advance master unit sorting terminal excitation in the y direction,

said command means including selectively operable x and y command circuits for initiating operation of said x and y control sections respectively.

9. The invention of claim 8,

said first and second switching means having reset conditions corresponding to excitation of the master unit sorting terminal of lowest coordinate address,

said x and control sections each having reset means for returning the respective switching means to its reset condition,

said x and y command circuits each having means for initiating operation of the reset means of the corresponding control section.

10. The invention of claim 9,

said circuit means coupling each of said devices between the corresponding remote unit sorting terminal and a common junction,

said exciting means further including a pair of electrical connection points adapted for coupling with a source of electrical energy, and an impedancepresenting element coupled between one of said points and each of said master unit sorting terminals respectively,

said first and second switching means being coupled with the other of said points for establishing electrical continuity between said other point and the master unit sorting terminal identified by said information,

said master unit being provided with voice transmitting and receiving means coupled in series with said master unit sorting terminal of lowest coordinate address and its associated element,

said remote unit being provided with voice transmitting and receiving means coupled in series between the remote unit sorting terminal of the same address as said lowest address and its associated indicating device, whereby to establish a communication circuit along the conductor intercoupling the terminals of lowest address and a path provided by the other conductors of the cable intercoupling the master and remote sorting terminals.

References Cited UNITED STATES PATENTS 2,488,556 11/1949 Parmenter 32466 2,806,995 9/1957 Meanley 179-175 KATHLEEN H. CLAFFY, Primary Examiner A. A. MCGILL, Assistant Examiner US. Cl. X.R. 

